It could be because the chunks at the back of the printer is not loaded, try to paint a picture, then save it. Go to the back of the printer and load the chunks, then upload the image that you saved to the screen, then try to print it! Hope it helps! =)

You know for those long stretches of redstone, instead of having the repeaters (Which i'm sure all add up to this lengthy time) you should just "Double reverse" it, by using a block and redstone torch to reverse it but also continue the signal, you then reverse it again a few blocks past and It is back to the input setting and is (However many) blocks further.But yeah, amazing design and idea really... I can see you put a crap tonne of effort in xD